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Quantum teleportation technique improved

18 June 2002

By Will Knight

Australian researchers claim to have significantly improved a technique for teleporting a laser beam across a distance of a few metres in a laboratory.

Researchers at the California Institute of Technology, Aarhus University in Denmark and the University of Wales in Bangor first demonstrated the teleportation of a laser beam consisting of millions of photons in 1998. Now a team led by Ping Koy Lam at the Australian National University in Canberra says they have made the process far more robust and reliable.

The teleportation technique makes use of quantum entanglement. When particles are fundamentally linked in this way, performing an operation on one will have the same effect on the other, even if they are physically separated.

Peter van Loock at the Universit”t Erlangen-N¸rnberg in Germany, who was involved in the 1998 experiment, says the Australian team has improved the method of creating entangled beams, which should give them a more accurate end result. But the improvement in accuracy is as yet unclear, he told New Scientist.

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“It’s definitely a new experiment, but I don’t know if it justifies being called the first really big breakthrough,” he adds.

Sougato Bose at Oxford University agrees. It seems the team has succeeded in teleporting a “brighter beam of light”, he says. “Probably this team has used a much stronger entanglement.”

Researchers hope quantum teleportation could be used to speed data communications. A brighter beam would mean more accurate information transfer, Bose says.

Distant dream

Lam’s team created two entangled light beams. They directed one of these beams towards the laser beam they wanted to teleport. And they directed the second of the entangled light beams to a separate location, a few metres away.

The first entangled light beam and the laser beam interacted. And the effect of this interaction on the light beam was automatically replicated in the second entangled beam, at the separate physical location.

Using measurements of the interaction effects on the first and on the second light beams, the team could precisely construct an exact copy of the original laser beam.

The interaction with the first entangled light beam meant the original laser beam was lost in the process.

Lam says that teleporting single atoms and molecules could be perfected within the next ten years. However, most researchers agree that teleporting large and complex objects remains a very distant dream.

Lam’s team will present their research at an international conference on quantum electronics to be held in Moscow next week.